When irrigation systems were first installed in the 1930s, the systems were activated manually and the valves controlling the systems were mounted on the surface of the ground if not above the ground entirely. In the 1950s, when irrigation systems adopted automatic activation, the automatic valves associated with these systems were generally buried, often with no marking as to their underground location. It soon became apparent, however, that knowledge of the underground valves' locations was necessary for routine service and maintenance. Further, even when underground valves were located, a wide area needed to be dug around them for accessibility and servicing.
Responding to these problems associated with buried valves, manufacturers and installers of irrigation systems began to mark the placement of underground valves and also to place the valves inside protective housings (i.e. “underground housings” such as boxes, pits or vaults). These underground housings were intended to enhance the accessibility of and to protect the underground valves and equipment.
As underground housings are presently constructed, these underground housings do not include a bottom surface. Instead, the ground provides the sixth “bottom-side” of the housing (see FIGS. 1A and 2A).
The described underground housings provide a number of advantages in allowing the placement of underground equipment. Moles, shrews, gophers and a number of other burrowing animals, however, can cause serious problems that detract from the benefits these underground housings were designed to provide.
When burrowing animals burrow in the vicinity of an underground housing, they often off-load displaced ground dirt or other debris (including, without limitation, rocks, gravel, etc.) into the space found within an underground housing. This off-loading is especially likely because burrowing animals often follow the path of an underground pipe or cable that leads to the location of an underground housing containing equipment related to the particular pipe or cable. At the location of the underground housing, the animals generally off-load ground dirt or other debris displaced by the burrowing because the empty air space provided by the underground housing provides a convenient place to do so.
The off-loading of displaced ground dirt or other debris by burrowing animals into underground housings causes numerous problems. First, the burrowing pushes large amounts of displaced ground dirt or other debris into the underground housing. This displaced ground dirt or other debris often covers the equipment within the underground housing thus reducing the accessibility of the equipment. Further, once displaced ground dirt or other debris has entered the space within an underground housing, roots from trees and shrubs soon follow. These roots entwine with themselves and the equipment within the underground housing, further limiting the accessibility of the equipment within the underground housing. Thus, once a burrowing animal has infiltrated an underground housing, a technician needing to access the equipment must not only dig out the off-loaded ground dirt or other debris but also must contend with roots tangled and entwined around valves, wires and other sensitive devices. This problem requires technicians to spend a great deal of time digging to the equipment found within an underground housing. This time reduces the productivity of these technicians and ultimately adds costs to consumers.
The displaced ground dirt or other debris and resulting roots found within underground housings caused by burrowing animals also can damage the equipment found within these underground housings. For example, many underground installations are designed or required to have open space around them. When displaced ground dirt or other debris and roots that would otherwise not exist in the housing reduce or eliminate the open space, excessive corrosion and premature failure often result.
Finally, most if not all states and water districts now require that irrigation systems include backflow assemblies to prevent the contamination of drinking water supplies from weed killers, fertilizers and animal waste (see, without limitation, Washington state code 246-290-490 and Utah state code 13.12). To prevent contamination of water supplies, many states also require that these underground backflow assemblies have at least a 12 inch clearance maintained below the assembly. If a burrowing animal infiltrates an underground space housing a backflow assembly, however, and displaced ground dirt or other debris and roots fill this space, the 12 inch clearance is not maintained and, in some cases, the backflow assembly can become completely buried. Both situations result in the violation of various health codes and poses a public health hazard.
Thus, while underground housings are intended to maintain the accessibility and integrity of the equipment contained therein, burrowing animals often reduce the effectiveness of these underground housings. Burrowing animals reduce the effectiveness of underground housings by off-loading displaced ground dirt and other debris in at least two ways: (1) up through the bottom of these underground housings, and/or (2) through small gaps that can be found around pipes or other cables entering or exiting the underground housing.